Add support for ANSI escape sequence for saving the current location of
the cursor "\e[s" and for recalling the last saved location "\e[u".
Note: if no location had been saved yet and the restore cursor
position (RPC) ANSI escape is received, defaults to 1,1 (top left of the
screen).
Signed-off-by: Collin J. Doering <collin.doering@rekahsoft.ca>